In a general sense, the invention is directed to systems and methods for treating interior tissue regions of the body. More specifically, the invention is directed to systems and methods for treating dysfunction in body sphincters and adjoining tissue, e.g., in and around the lower esophageal sphincter and cardia of the stomach.
As FIG. 1 shows, the esophagus 10 is a muscular tube that carries food from the mouth into the stomach 12. The muscles in the walls of the esophagus 10 contract in a wavelike manner, moving the food down to the stomach 12. The interior wall of the esophagus includes glands that secrete mucus, to aid in the movement of food by providing lubrication. The human esophagus is about twenty-five centimeters long.
The stomach 12, located in the upper left hand side of the abdomen, lays between the esophagus 10 and the small intestine 14. In people and most animals, the stomach 12 is a simple baglike organ. A human being""s stomach is shaped much like a J.
The average adult stomach can hold a little over one quart (0.95 liter). The stomach 12 serves as a storage place for food. Food in the stomach 12 is discharged slowly into the intestines 14. The stomach 12 also helps digest food.
The upper end of the stomach connects with the esophagus 10 at the cardiac notch 16, at the top of the J-shape. The muscular ring called the lower esophageal sphincter 18 surrounds the opening between the esophagus 10 and the stomach 12. The funnel-shaped region of the stomach 12 immediately adjacent to the sphincter 18 is called the cardia 20. The cardia 20 comprises smooth muscle. It is not a sphincter.
The lower esophageal sphincter 18 relaxes, or opens, to allow swallowed food to enter the stomach 12. The lower esophageal sphincter 18, however, is normally closed, to keep the stomach 12 contents from flowing back into the esophagus 10.
Another sphincter, called the pyloric sphincter 22, surrounds the duodenal opening of the stomach 12. The pyloric sphincter 22 keeps non-liquid food material in the stomach 12 until it is processed into a more flowable, liquid form. The time that the stomach 12 retains food varies. Usually, the stomach 12 empties in three to five hours.
In a person suffering from gastrointestinal reflux disease (GERD), the lower esophageal sphincter 18 is subject to spontaneous relaxation. The sphincter 18 opens independent of the normal swallowing function. Acidic stomach contents surge upward into the esophagus 10, causing pain, discomfort, and damage the mucosal wall of the esophagus 10.
The stomach 12 distends to accommodate various food volumes. Over time, stomach distention can stretch the cardia 20 or otherwise cause loss of compliance in the cardia 20. Loss of compliance in the cardia 20 can also pull the lower esophageal sphincter 18 open when the stomach 12 is distended, even absent sphincter muscle relaxation. The same undesired results occur: acidic stomach contents can surge upward into the esophagus 10. Unlike the stomach, the esophagus has no natural protection against stomach acids. When the stomach contents make contact with the esophagus, heartburn or other disease symptoms, including damage to the esophagus, can occur.
Complications of GERD include esophageal erosion, esophageal ulcer, and esophageal stricture; replacement of normal esophageal epithelium with abnormal (Barrett""s) epithelium; and pulmonary aspiration.
One aspect of the invention provides systems and methods for treating a targeted tissue region with a tissue heating element. The tissue heating element is incorporated in a carrier. The carrier is intended, in use, to be temporarily mounted to an exterior of an independent catheter body, such as an endoscope. The catheter body is deployed, with the carrier mounted on it, into the targeted tissue region. The tissue heating element is operated, e.g., to form one or more tissue lesions, after which the catheter body is retrieved from the targeted tissue region. The carrier can then be removed from the catheter body, allowing the catheter body to be subsequently used for another purpose.
In one embodiment, the systems and methods can be used to treat tissue regions along the gastrointestinal track, e.g., in and around the lower esophageal sphincter, to treat GERD and related dysfunctions.